Orthopedic measurement devices, systems and methods

ABSTRACT

A device for orthopedic measurements includes a main housing, a center member, a measurement indicator, and a flexible member. The main housing has a proximal end with a top opening and a distal end with a side opening, and defines a longitudinal axis and includes a main housing cavity. The center member is disposed along the longitudinal axis within the main housing cavity. The measurement indicator is operatively connected to the center member, and is configured and adapted to display a measurement of a distance. The flexible member is threaded through the main housing cavity, and includes a first end and an opposed second end with an eyelet disposed proximate the side opening of the main housing. The eyelet is configured to be drawn away from the main housing, extending the flexible member outward with respect to the side opening to display a measurement on the measurement indicator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/695,578 filed Aug. 31, 2012 which is incorporated by referenceherein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to orthopedic surgical procedures and moreparticularly to methods and apparatuses for orthopedic measurements.

2. Description of Related Art

Presently, there is no known way to accurately measure the proper sizefor an orthopedic prosthesis implant, such as a cervical plate, or thelike. Traditional methods to determine the correct size require trialand error. As one example, anterior cervical decompression and fusion isperformed through a small transverse skin incision in the front of theneck. The procedure involves the removal of one or more spinal discs todecompress the spinal cord and exiting nerve roots. The spinal discheights are increased because the discs are replaced with bone grafts todecompress the exiting nerve roots. Before placing the grafts, thesurgeon templates for the height of the disc spaces with wedges, orspacers, of known dimensions. The spacers are then removed and thegrafts are placed. Following the placement of grafts, the surgeon musttunnel a long cervical plate down to the spine for fusions of one ormore disc spaces. The length of the plates is minimized in order toavoid adjacent segment degeneration, making accuracy crucial. Often, thefirst plate chosen and placed in position is either too short or toolong. In order to determine the correct plate, a surgeon must remove theincorrect length plate and try another size plate. This method of trialand error requires additional soft tissue retraction causing additionaltrauma to the tissue resulting in longer recovery time and increasedscar tissue. It also increases the time required to perform theprocedure and the chance of concomitant risks.

Such conventional methods and systems have generally been consideredsatisfactory for their intended purpose. However, there is still a needin the art for methods and apparatuses that allow for improved accuracyin orthopedic measurement, e.g., when performing anterior cervicaldecompression and fusion, when determining the proper size for anorthopedic prosthesis implant or the like. There also remains a need inthe art for such methods and apparatuses that are easy to make and use.The present invention provides a solution for these problems.

SUMMARY OF THE INVENTION

The subject invention is directed to a new and useful device fororthopedic measurements. The device includes a main housing, a centermember, a measurement indicator, and a flexible member.

The main housing has a proximal end and a distal end, the proximal endhaving a top opening and the distal end having a side opening, whereinthe main housing defines a longitudinal axis and includes a main housingcavity. The center member is disposed along the longitudinal axis withinthe main housing cavity, wherein the center member is configured andadapted to move along the longitudinal axis relative to the mainhousing. The measurement indicator is operatively connected to thecenter member, and is configured and adapted to display a measurement ofa distance. The flexible member includes a first end and an opposedsecond end. The second end has an eyelet. The flexible member isthreaded through the main housing cavity and the eyelet is disposedproximate the side opening of the main housing. The eyelet is configuredand adapted to be drawn away from the main housing, extending theflexible member outward with respect to the side opening to display ameasurement on the measurement indicator.

In accordance with certain embodiments, the device for orthopedicmeasurements can include a spring disposed in the main housing cavityalong the longitudinal axis between the side opening and the topopening. The spring can be operatively connected to bias the centermember along the longitudinal axis away from the distal end of the mainhousing. Further, the spring can be disposed between the top opening andthe flexible member, and can surround and operatively connect to thecenter member. Or, the spring can be disposed between a distal end ofthe center member and the distal end of the main housing, operativelyconnected to the center member. In both cases, the spring can be biasedalong the longitudinal axis such that the flexible member is biasedtoward an undeployed position.

In further accordance with certain embodiments, the flexible member canbe operatively connected to the center member, and/or can be operativelyconnected to the distal end of the center member and threaded throughthe spring along the longitudinal axis, so that movement of the centermember against a bias force of the spring along the longitudinal axisdrives the flexible member outward through the side opening.

In further accordance with certain embodiments, a portion of the centermember can extend out of the main housing through the top opening at theproximal end. The measurement indicator can be at least partiallydisposed on the portion of the center member that extends out of themain housing. In addition, the main housing cavity can include a cammedsurface between the center member and the distal end of the mainhousing, wherein the cammed surface can be configured and adapted toguide the flexible member in and out of the main housing through theside opening-substantially orthogonal to the longitudinal axis of themain housing. Further, the eyelet can be disposed outside of the mainhousing cavity and can be larger than the side opening to prevent itfrom being drawn into the main housing cavity.

The subject invention is also directed to a new and useful method ofperforming orthopedic measurements. The method includes inserting ameasurement tool into an incision, securing an eyelet of the measurementtool on a tack, the eyelet being operatively connected to a flexiblemember, moving the measurement tool away from the tack, wherein themovement deploys the flexible member, and displaying a measurementindicative of the distance between the measurement tool and the tack.

The subject invention is also directed to a device for orthopedicmeasurements that can measure between, for example, two tacks, spacers,or the like. The device includes a main housing that has a proximal endand a distal end, the proximal end has a top opening and the distal endhas opposed first and second side openings. The main housing defines alongitudinal axis and includes a main housing cavity. The device alsoincludes a center member disposed along the longitudinal axis within themain housing cavity. A portion of the center member extends out of themain housing through the top opening at the proximal end. The centermember is configured and adapted to move along the longitudinal axisrelative to the main housing. The device also includes a measurementindicator operatively connected to the center member and configured andadapted to display a measurement of a distance. The device also includesa cable including a first and a second end. Each cable end has aneyelet. The cable is threaded through the main housing cavity and theeyelets are disposed proximate the first and second side openings,respectively, of the main housing. The eyelets are configured andadapted to be drawn away from the main housing, extending the cableoutward with respect to the side openings, and displaying a measurementon the measurement indicator.

In accordance with certain embodiments, the measurement indicator can bemuch as described above. The device can also include a center pulleywheel disposed on the center member within the main housing cavitybetween the measurement indicator and the distal end along thelongitudinal axis. The center pulley wheel can be configured and adaptedto move with the center member along the longitudinal axis relative tothe main housing and to rotate about a pulley axis. The device canfurther include a spring disposed in the main housing cavity along thelongitudinal axis between the center pulley wheel and the distal end.The spring can be configured and adapted to bias the center member alongthe longitudinal axis away from the distal end of the main housing. Thedevice can also include two side pulleys. A first side pulley wheel canbe mounted within the main housing cavity proximate the first sideopening configured and adapted to rotate about a pulley axis. A secondside pulley wheel can be mounted within the main housing cavityproximate the second opening configured and adapted to rotate about apulley axis. The cable can be threaded through the first and second sidepulley wheels, such that the first end extends through the first sideopening and the second end extends through the second side opening,thereby moving the center pulley wheel and the center member along thelongitudinal axis relative to the main housing against the bias force ofthe spring when either or both of the eyelets extend outward, anddisplay a measurement on the measurement indicator.

In further accordance with certain embodiments, the cable can bethreaded between the center pulley wheel and the center member. Thefirst end can be threaded down through the main housing cavity, aroundthe first side pulley wheel, and out through the first side opening. Thesecond end can be threaded down through the main housing cavity, aroundthe second side pulley wheel and out through the second side opening.The eyelets can be disposed outside of the main housing cavity flushwith the main housing and can be larger than the first and second sideopenings to prevent them from being drawn into the main housing cavity.

The invention also provides a method of performing orthopedicmeasurements, for example, between two tacks, spacers, or the like. Themethod includes inserting a measurement tool into an incision, securinga first eyelet of the measurement tool on a first spacer post, e.g.embedded in a spine or other orthopedic location, moving the measurementtool away from the first spacer post towards a second spacer post,securing a second eyelet of the measurement tool to the second spacerpost, and displaying a measurement indicative of the distance betweenthe spacer posts, for example, to aid in determining the proper size foran orthopedic prosthesis implant or the like.

The invention also provides a kit for performing orthopedicmeasurements. The kit includes a device for orthopedic measurements, asdescribed above, a plurality of spacers with posts, and a removablespacer placement tool configured and adapted to enter an incision andplace the spacers.

These and other features of the systems and methods of the subjectinvention will become more readily apparent to those skilled in the artfrom the following detailed description of the preferred embodimentstaken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those skilled in the art to which the subject inventionappertains will readily understand how to make and use the devices andmethods of the subject invention without undue experimentation,preferred embodiments thereof will be described in detail herein belowwith reference to certain figures, wherein:

FIG. 1 is a perspective view of an exemplary embodiment of a device fororthopedic measurements constructed in accordance with the presentinvention;

FIG. 2 is an exploded perspective view of the device of FIG. 1;

FIG. 3 is a perspective view of a cable of the device of FIG. 1;

FIG. 4 is a perspective view of an exemplary embodiment of a spacerconstructed in accordance with the present invention;

FIG. 5 is a perspective view of an exemplary embodiment of a removablespacer placement tool constructed in accordance with the presentinvention, showing the tool threaded into the spacer of FIG. 4;

FIG. 6 is a perspective view of a spinal model showing placement of thespacers of FIG. 4 in the spine and showing the removable spacerplacement tool of FIG. 5;

FIG. 7 is a perspective view of the spinal model of FIG. 6, showing astep of hooking a first eyelet on a first spacer;

FIG. 8 is a perspective view of the spinal model of FIG. 6, showing astep of hooking a second eyelet on a second spacer to take ameasurement;

FIG. 9 is an exploded perspective view of an exemplary embodiment of akit in accordance with the present invention;

FIG. 10 is a perspective view of another exemplary embodiment of adevice for orthopedic measurements constructed in accordance with thepresent invention;

FIG. 11 is a cross-sectional view of the device of FIG. 10, showing aflexible member and spring within a main housing cavity;

FIG. 12 is a perspective view of a spinal model showing a first tack anda second tack placed in the spine and the device of FIG. 10;

FIG. 13 is a partial enlarged perspective view of the spinal model ofFIG. 12, showing a step of securing an eyelet of the device of FIG. 10on the first tack;

FIG. 14 is a perspective view of the spinal model of FIG. 12, showing astep of moving the device of FIG. 10 away from the first tack anddeploying a flexible member; and

FIG. 15 is a cross-sectional view of the device of FIG. 10, showing theflexible member in a deployed position, and a measurement displayed on ameasurement indicator.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made to the drawings wherein like referencenumerals identify similar structural features or aspects of the subjectinvention. For purposes of explanation and illustration, and notlimitation, a partial view of an exemplary embodiment of the device fororthopedic measurements in accordance with the invention is shown inFIG. 1 and is designated generally by reference character 100. Otherembodiments of the device in accordance with the invention, or aspectsthereof, are provided in FIGS. 2-15 as will be described.

Referring now to FIG. 1, the subject invention is directed to a new anduseful device for orthopedic measurements 100. Device 100 includes amain housing 102 that has a proximal end 104 and a distal end 106,proximal end 104 has a top opening 108 and distal end 106 has opposedfirst and second side openings 110, 112, respectively. Main housing 102defines a longitudinal axis A and includes a main housing cavity 114,shown in FIG. 2. Device 100 also includes a center member 116 disposedalong longitudinal axis A within main housing cavity 114. A portion ofcenter member 116 extends out of main housing 102 through top opening108 at proximal end 104. Center member 116 is configured and adapted tomove along longitudinal axis A relative to main housing 102. Device 100also includes a measurement indicator 118 on center member 116.Measurement indicator 118 is at least partially disposed on the portionof the center member 116 that extends out of the main housing 102 and isconfigured and adapted to display a measurement of a distance with aseries of graduations marked around center member 116. Those skilled inthe art will readily appreciate that a measurement indicator can insteadbe digital, dial based or any other suitable type of indicator can beused instead of graduations on a protruding member, without departingfrom the spirit and scope of the invention.

With reference now to FIG. 2, the device also includes a center pulleywheel 120 disposed on center member 116 within main housing cavity 114between measurement indicator 118 and distal end 106 along longitudinalaxis A. Center pulley wheel 120 is configured and adapted to move withcenter member 116 along longitudinal axis A relative to main housing 102and to rotate about a pulley axis B. Device 100 further includes aspring 122 disposed in main housing cavity 114 along longitudinal axis Abetween center pulley 120 wheel and distal end 106. Spring 122 isconfigured and adapted to bias center member 116 along longitudinal axisA away from distal end 106 of main housing 102. Device 100 also includestwo side pulleys 124, 126. A first side pulley wheel 124 is mountedwithin main housing cavity 114 proximate first side opening 110configured and adapted to rotate about a pulley axis C. A second sidepulley wheel 126 is mounted within main housing cavity 114 proximatesecond side opening 112 configured and adapted to rotate about a pulleyaxis D.

Referring now to FIGS. 2 and 3, device 100 also includes a cable 128including a first end 130 and a second end 132. Each cable end 130,132has an eyelet 134. FIG. 3 shows cable 128 and eyelets 134 removed frommain housing 102. As shown in FIG. 2, cable 128 is threaded through thecenter pulley wheel 120 and each of first and second side pulley wheels124,126, such that first end 130 extends through first side opening 110and second end extends through second side opening 112, and wherein theeyelets 134 are disposed proximate first and second side openings110,112, respectively, of the main housing 102. Eyelets 134 areconfigured and adapted to be drawn away from the main housing 102,extending cable 128 outward with respect to side openings 110, 112,thereby moving center pulley wheel 120 and center member 116 inwardalong longitudinal axis A relative to main housing 102 against the biasforce of spring 122 when either or both of the eyelets 134 are extendedoutward to display a measurement on measurement indicator 118. Themeasurement can be determined by reading or counting the graduations ofmeasurement indicator 118.

With continued reference to FIG. 2, in accordance with certainembodiments, cable 128 is threaded between center pulley wheel 120 andthe center member 116. The first end 130 is threaded down through mainhousing cavity 114, around first side pulley wheel 124, and out throughfirst side opening 110. Second end 132 is threaded down through mainhousing cavity 114, around second side pulley wheel 126 and out throughsecond side opening 112. In other words, cable 128 is threaded under thefirst side pulley wheel 124, over the center pulley wheel 120, and underthe second side pulley wheel 126. Eyelets 134 are disposed outside ofmain housing cavity 114 flush with main housing 102 and are larger thanfirst and second 110, 112 side openings to prevent them from being drawninto main housing cavity 114.

Those skilled in the art will readily appreciate that a device fororthopedic measurements, e.g. device 100, can be disposable, forexample, made of a plastic or other disposable material and can bepackaged and sold sterile, or it can be reusable and be configured to becleaned and sterilized.

Referring now to FIGS. 4-8, the invention also provides a method ofperforming orthopedic measurements. As discussed above, in anteriorcervical decompression and fusion, the spinal disc height is increasedby placing bone grafts. Traditionally, before placing the grafts,surgeons template for the height of the disc spaces with spacers ofknown dimensions. As shown in FIG. 4, in accordance with the invention,spacers 136 used to template for the height of the disc spaces haveposts 138 to accommodate for using the measurement device, e.g. device100, therein allowing the spacer to serve two purposes while decreasingthe invasiveness of the surgery.

Referring to FIGS. 5 and 6, spacer 136 is affixed to a removable spacerplacement tool 140, which is threaded into threaded bore 137 of spacer136 in FIG. 5. The removable spacer placement tool, e.g. placement tool140, implants the first spacer, e.g. spacer 136, into a spinal discspace, as shown in FIG. 6. It is then unthreaded, and removed from thespacer, leaving the first spacer implanted. The same placement tool,e.g. placement tool 140, is then threaded into the threaded bore, e.g.threaded bore 137, of a second spacer, e.g. spacer 136, and affixed tothe second spacer. The steps described above performed with the firstspacer are then repeated with the second spacer.

As shown in FIGS. 7-8, the method includes inserting a measurement tool,e.g. device 100, into an incision, securing a first eyelet, e.g. eitherof eyelets 134, of the measurement tool on a first spacer post, e.g.post 138, as shown in FIG. 7, moving the measurement tool away from thefirst spacer post towards a second spacer post, securing a secondeyelet, e.g. either of eyelets 134 of the measurement tool to the secondspacer post, as shown in FIG. 8, and displaying a measurement indicativeof the distance between the spacer posts, for example, to aid indetermining the proper size for an orthopedic prosthesis implant or thelike.

In addition, those skilled in the art will readily appreciate that themeasurement device can be calibrated to display appropriate measurementsindicative of the height or length needed for the orthopedic prostheticimplant. For example, if the measurement tool is being used to performanterior cervical decompression and fusion, the measurement tool, e.g.device 100, can be calibrated to display the distance between theendplates of the one or more spinal discs as opposed to the distancebetween the spacer posts. Further, those skilled in the art will readilyappreciate that instead of substantially vertical posts on the spacers,like those shown in the Figures, the posts can be laterally off-set ascompared with the posts shown in FIG. 6. For example, the posts can beshaped to overhang their respective endplates so the posts are locatedwhere the bone screws will ultimately be placed. This overhanging postcan provide a more accurate measurement between the endplates and cannegate the need for calibration.

Those skilled in the art will also readily appreciate that eyelets 134can also be placed on tacks. For example, tacks can be used totemporarily affix the plates prior to screw fixation. Tacks can beplaced in the vertebral body at the superior and inferior ends of thefusion and can directly indicate where the screws to secure the platewill be fixed. By placing the eyelets 134 on tacks, there is no need toadd additional length to the measurement because the distance betweentacks is a direct indication of the plate length required.

Those skilled in the art will also readily appreciate that the housing,e.g. housing 102, need not be centered between eyelets, e.g. eyelets134, during a measurement. In other words, the distance measurementreading is constant regardless of relative position of the housingbetween eyelets.

Referring to FIG. 9, the invention also provides a kit 200 forperforming orthopedic measurements. Kit 200 includes a device fororthopedic measurements 202, a plurality of spacers 204 with posts, anda removable spacer placement tool 206, all as described above.

Referring to FIG. 10, another embodiment of a new and useful device 300for orthopedic measurements is shown. Device 300 includes a main housing302, a center member 316, a measurement indicator 318, and a flexiblemember 328. Main housing 302 has a proximal end 304 and a distal end306, proximal end 304 having a top opening 308 and distal end 306 havinga side opening 310, wherein main housing 302 defines a longitudinal axisA and includes a main housing cavity 314, shown in FIG. 11. Centermember 316 is disposed along longitudinal axis A within main housingcavity 314, wherein center member 316 is configured and adapted to movealong longitudinal axis A relative to main housing 302. Measurementindicator 318 is operatively connected to center member 316, and isconfigured and adapted to display a measurement of a distance.Measurement indicator 318 is similar to measurement indicator 118 andits variations, as described above, and can be similarly calibrated. Aportion of center member 316 extends out of main housing 302 through topopening 308 at proximal end 304. Measurement indicator 318 is at leastpartially disposed on the portion of center member 316 that extends outof main housing 302.

Referring now to FIG. 11, flexible member 328 includes a first end 330and an opposed second end 332. Second end 332 has an eyelet 334.Flexible member 328 is threaded through main housing cavity 314 andeyelet 334 is disposed proximate side opening 310 of main housing 302.Main housing cavity 314 includes a cammed surface 315 between centermember 316 and distal end 306 of the housing. Those skilled in the artwill readily appreciate that cammed surface 315 is configured andadapted to guide flexible member 328 in and out of main housing 302through side opening 310 substantially orthogonal to longitudinal axis Aof main housing 302. Eyelet 334 is configured and adapted to be drawnaway from main housing 302, extending flexible member 328 outward withrespect to side opening 310 to display a measurement on measurementindicator 318. Eyelet 334 is disposed outside of main housing cavity 314and is larger than side opening 310 to prevent it from being drawn intomain housing cavity 314.

With further reference to FIG. 11, device 300 for orthopedicmeasurements includes a spring 322. Spring 322 is operatively connectedto bias center member 316 along longitudinal axis A away from distal end306 of main housing 302. Spring 322 is disposed between a distal end 317of center member 316 and distal end 306 of the housing, operativelyconnected to center member 316. Flexible member 328 is operativelyconnected to distal end 317 of center member 316 and threaded throughspring 322 along the longitudinal axis, so that movement of centermember 316 against a bias force of spring 322 along longitudinal axis Adrives flexible member 328 outward through side opening 310. Thoseskilled in the art will readily appreciate that the movement of centermember 316 against the bias force of spring 322 is not required fordeployment of flexible member 328. For example, those skilled in the artwill readily appreciate that the force generated by pulling device 300away from tack 336, while eyelet 334 is affixed to tack 336, asdescribed below, would be sufficient to bias spring 322 and deployflexible member 328.

Those skilled in the art will readily appreciate that spring 322 can bedisposed anywhere in main housing cavity 314 along longitudinal axis Abetween side opening 310 and top opening 308. For example, those skilledin the art will readily appreciate that spring 322 can be disposedbetween top opening 308 and flexible member 328, and can surround andoperatively connect to center member 316, or can be in any suitablearrangement so that spring 322 is biased along longitudinal axis A suchthat flexible member 328 is biased toward an undeployed position.Furthermore, those skilled in the art will readily appreciate that adevice for orthopedic measurements, e.g. device 300, can be disposableas described above.

Referring now to FIGS. 12-15, the invention also provides a method ofperforming orthopedic measurements without spacers 136, as describedabove. As shown in FIG. 12, instead of spacers 136, tacks 336 are used.FIG. 12 shows a spinal model showing a first tack 336 and a second tack336 placed in the spine. Those skilled in the art will readilyappreciate that there are many scenarios that require orthopedic in-situmeasurements without also requiring the insertion of spacers 136, as wasdiscussed above. By using tacks 336 instead of spacers 136, device 300can be used to take a variety of orthopedic measurements.

With further reference to FIGS. 12-15, tacks 336 have heads 338 toaccommodate for the securing of eyelet 334. The method includesinserting measurement tool, e.g. device 300, into an incision, securingan eyelet, e.g. eyelet 334, of the measurement tool on a first tack,e.g. tack 336, the eyelet being operatively connected to a flexiblemember, e.g. flexible member 328, as shown in FIG. 13, moving themeasurement tool away from the first tack, wherein the movement deploysthe flexible member and displays a measurement, e.g. measurement m, onthe measurement indicator, e.g. measurement indicator 318, indicative ofthe distance between the measurement tool and the tack, as shown inFIGS. 14 and 15. When the back of device 300 contacts the second tack336, as illustrated in FIG. 14, the span between the tacks can bedetermined from the displayed measurement m, e.g., by calibratingmeasurement m to account for the width of device 300 in the measurementdirection. The sites where tacks 336 are placed can be selected assuitable sites ultimately used for bone screws, so measurement m can beused to directly select an implant with the proper spacing betweenscrews, for example.

Those skilled in the art will readily appreciate that, although twotacks 336 are shown in FIGS. 12, and 14-15, the method can be performedwith a single tack 336, or any other suitable number of tacks 336appropriate for a given application. In addition, those skilled in theart will readily appreciate that tacks 336 without heads 338 and avariety of tack 336 shapes and sizes can be used. Further, those skilledin the art will readily appreciate that, kit 200, described above, forperforming orthopedic measurements, can easily include alternativemeasurement tools, for example, device 300 and accompanying accessoriessuch as tacks 336, as described above.

Those skilled in the art will readily appreciate that any other suitableorthopedic application can attain the advantages described hereinwithout departing from the spirit and scope of the invention. Forexample, the orthopedic measurement tool can be used in the cervicalspine, thoracic spine, lumbar spine, glenohumoral joint, hip joint,wrist, or in any other suitable location. The systems and methods of theinvention increase measurement accuracy and provide for a less invasiveway of performing orthopedic measurements.

Those skilled in the art will also readily appreciate that the methodsand devices described above can also be applied or adapted to any othersuitable procedure without departing from the spirit and scope of theinvention. The devices, methods and systems of the present invention, asdescribed above and shown in the drawings, provide for a device forperforming orthopedic measurements with superior properties includingaccuracy, ease of use and ease of manufacture. While the apparatus andmethods of the subject invention have been shown and described withreference to preferred embodiments, those skilled in the art willreadily appreciate that changes and/or modifications may be made theretowithout departing from the spirit and scope of the subject invention.

What is claimed is:
 1. A device for orthopedic measurements, comprising a main housing having a proximal end and a distal end, the proximal end having a top opening and the distal end having a side opening, wherein the main housing defines a longitudinal axis and includes a main housing cavity; a center member disposed along the longitudinal axis within the main housing cavity, wherein the center member is configured and adapted to move along the longitudinal axis relative to the main housing; a measurement indicator operatively connected to the center member, configured and adapted to display a measurement of a distance; and a flexible member including a first end and an opposed second end, the second end having an eyelet, wherein the flexible member is threaded through the main housing cavity and wherein the eyelet is disposed proximate the side opening of the main housing and is configured and adapted to be drawn away from the main housing extending the flexible member outward with respect to the side opening to display a measurement on the measurement indicator.
 2. A device for orthopedic measurements as recited in claim 1, further comprising a spring disposed in the main housing cavity along the longitudinal axis between the side opening and the top opening, wherein the spring is operatively connected to bias the center member along the longitudinal axis away from the distal end of the main housing.
 3. A device for orthopedic measurements as recited in claim 2, wherein the spring is disposed between the top opening and the flexible member, and surrounds and operatively connects to the center member, wherein the spring is biased along the longitudinal axis such that the flexible member is biased toward an undeployed position.
 4. A device for orthopedic measurements as recited in claim 2, wherein the flexible member is operatively connected to the center member so that movement of the center member against a bias force of the spring along the longitudinal axis drives the flexible member outward through the side opening.
 5. A device for orthopedic measurements as recited in claim 2, wherein the spring is disposed between a distal end of the center member and the distal end of the main housing, and operatively connects to the center member, wherein the spring is biased along the longitudinal axis such that the flexible member is in an undeployed position.
 6. A device for orthopedic measurements as recited in claim 5, wherein the flexible member is threaded through the spring along the longitudinal axis and operatively connected to the distal end of the center member, wherein movement of the center member against a bias force of the spring along the longitudinal axis drives the flexible member outward through the side opening.
 7. A device for orthopedic measurements as recited in claim 1, wherein a portion of the center member extends out of the main housing through the top opening at the proximal end.
 8. A device for orthopedic measurements as recited in claim 7, wherein the measurement indicator is at least partially disposed on the portion of the center member that extends out of the main housing.
 9. A device for orthopedic measurements as recited in claim 1, wherein the main housing cavity includes a cammed surface between the center member and the distal end of the main housing, wherein the cammed surface is configured and adapted to guide the flexible member in and out of the main housing through the side opening-substantially orthogonal to the longitudinal axis of the main housing.
 10. A device for orthopedic measurements as recited in claim 1, wherein the eyelet is disposed outside of the main housing cavity flush with the main housing and is larger than the side opening to prevent it from being drawn into the main housing cavity.
 11. A method of performing orthopedic measurements, comprising inserting a measurement tool into an incision; securing an eyelet of the measurement tool on a tack, the eyelet being operatively connected to a flexible member; moving the measurement tool away from the tack, wherein the movement deploys the flexible member; and displaying a measurement indicative of the distance between the tool and the tack.
 12. A device for orthopedic measurements, comprising a main housing having a proximal end and a distal end, the proximal end having a top opening and the distal end having opposed first and second side openings, wherein the main housing defines a longitudinal axis and includes a main housing cavity; a center member disposed along the longitudinal axis within the main housing cavity, wherein the center member is configured and adapted to move along the longitudinal axis relative to the main housing; a measurement indicator operatively connected to the center member, configured and adapted to display a measurement of a distance; and a cable including a first and a second end, each cable end having an eyelet, wherein the cable is threaded through the main housing cavity and wherein the eyelets are disposed proximate the first and second side openings, respectively, of the main housing, and are configured and adapted to be drawn away from the main housing extending the cable outward with respect to the side openings, and displaying a measurement on the measurement indicator.
 13. A device for orthopedic measurements as recited in claim 12, wherein a portion of the center member extends out of the main housing through the top opening at the proximal end.
 14. A device for orthopedic measurements as recited in claim 13, wherein the measurement indicator is at least partially disposed on the portion of the center member that extends out of the main housing.
 15. A device for orthopedic measurements as recited in claim 12, further comprising: a center pulley wheel disposed on the center member within the main housing cavity between the measurement indicator and the distal end along the longitudinal axis, wherein the center pulley wheel is configured and adapted to move with the center member along the longitudinal axis relative to the main housing and to rotate about a pulley axis; a spring disposed in the main housing cavity along the longitudinal axis between the center pulley wheel and the distal end, wherein the spring is configured and adapted to bias the center member along the longitudinal axis away from the distal end of the main housing; a first side pulley wheel mounted within the main housing cavity proximate the first side opening configured and adapted to rotate about a pulley axis; and a second side pulley wheel mounted within the main housing cavity proximate the second side opening configured and adapted to rotate about a pulley axis.
 16. A device for orthopedic measurements as recited in claim 15, wherein the cable is threaded through the center, first side and second side pulley wheels, such that the first end extends through the first side opening and the second end extends through the second side opening.
 17. A device for orthopedic measurements as recited in claim 15, wherein the cable is routed to move the center pulley wheel and the center member along the longitudinal axis relative to the main housing against a bias force of the spring when either or both of the eyelets extend outward from the main housing.
 18. A device for orthopedic measurements as recited in claim 15, wherein the cable is threaded between the center pulley wheel and the center member, the first end threaded down through the main housing cavity, around the first side pulley wheel, and out through the first side opening, the second end threaded down through the main housing cavity, around the second side pulley wheel and out through the second side opening.
 19. A device for orthopedic measurements as recited in claim 12, wherein the eyelets are disposed outside of the main housing cavity flush with the main housing and are larger than the first and second side openings to prevent them from being drawn into the main housing cavity.
 20. A method of performing orthopedic measurements, comprising inserting a measurement tool into an incision; securing a first eyelet of the measurement tool on a first spacer post; moving the measurement tool away from the first spacer post towards a second spacer post; securing a second eyelet of the measurement tool to the second spacer post; and displaying a measurement indicative of the distance between the spacer posts. 